<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>$课堂练习$</title>
</head>
<body>
<script>
    var jb = prompt("请输入级别");
    switch (jb) {
        case "A":
            console.log("90到100之间");
            break;
        case "B":
            console.log("80到90之间");
            break;
        case "C":
            console.log("70到80之间");
            break;
        case "D":
            console.log("60到70之间");
            break;
        default:
            console.log("0到50之间");
    }
    //比较是严格模式
</script>
</body>
</html>